Serious crash near Stanwood tangles traffic, closes southbound I-5

All lanes of southbound Interstate 5 were closed near Stanwood in Snohomish County after a serious crash.

The lanes have since reopened.

The Washington State Department of Transportation first reported the incident just north of 300th Street Northwest at 4:37 a.m. Tuesday.

It is not yet known how many cars were involved or if anyone was hurt.

As of 5 a.m., traffic was backed up about 4 miles.

All lanes reopened shortly before 6 a.m.